The duct lines and pipelines are lines used for carrying fluids, such as hydrocarbon oil and derivatives, chemical products, alcohol and water, which according to their application are designated as oil pipelines, gas pipelines, aqueducts, polyducts or alcohol ducts. Such flow lines are built using mid-sized and large-sized pipes that extend over great distances overland.
The method of building duct lines/pipelines in general consists in the building of pipes, the distribution thereof along their intended trajectory and the assembly of the distribution line by connecting the pipes to one another.
Many difficulties are encountered while building such type of distribution line in view of the large size of the pipes employed for that purpose and the environmental, geographical and weather constraints that must be overcome, and in this regard it is necessary to make use of large and heavy equipment to move and lay the pipes in place.
The traditional method used to assemble ducts intended to carry fluids (oil pipelines, adductors, gas pipelines, ducts for other derivatives, water mains, etc.) consists in transporting the pipes of convenient length for each use until the assembly site where they are placed forming a line (in an arrangement approximately parallel along the course of the line and near their respective positions in pre-joined sets) by means of welding. The operations of positioning and adjustment for welding are performed at the definitive location, and therefore the rigging team is itinerant, performing their work from point to point along the course of the line as the pipeline advances. To that end, there are crated new accesses to each point, the equipment must be transported, the installations must be disassembled and reassembled at new positions entailing frequent logistics difficulties, implying a substantial increase in costs, risks, and particularly of work time. Bad weather conditions, in such context, almost always cause the work to be interrupted.
In a great number of cases, however, it is noted that the traditional method requires that the pipes (or ducts) be transported to locations of difficult access, or unhealthy or hazardous, and furthermore, the assembly operations consisting in positioning, welding, tests and quality checks, etc. are performed at the locations where each length of pipe will be definitively installed, which might be quite difficult or even impossible depending on the particular situation, causing an increase in performance delay, loss of quality, costs, personal risks, material risks and environmental hazard.
The known methods of building duct lines/pipelines require the work site to be mobile and follow the team in charge of performing the welding of the ducts that are aligned in the place where they will stay when the duct line is finished. This requires the creation of access ways to the welding points between ducts, often requiring expropriation of real property or the establishment of rights of way, rendering the building work more expensive and delaying the same.
The project of construction of duct lines/pipelines encounters situations where the trajectory of the line passes through tunnels, galleries, and congested industrial facilities.
In such cases, according to the processes commonly used in the art, there is performed a partial or total disassembly of the existing facilities and the reassembly thereof subsequently to the building of the distribution line, often with a consequent interruption of production.
One other factor that interferes with the traditional systems for laying duct lines/pipelines consists in lengths of the trajectory of such distribution lines with geological or topographical hindrances that limit the transit of heavy equipment or being even devoid of any condition of access for performance of work in the installation site, such as crossings through marshy locations, snow, ice, areas with human occupation, archaeological sites, etc.
The above mentioned factors generally determine the definition or alteration of the paths to be followed by the lines, with major implications in terms of cost, time and logistics.
One other approach used in an attempt to overcome the above described problems, and which also constitutes a classic formula for assembling duct lines/pipelines, consists in joining a certain number of pipes, forming a longer section of piping, and subsequently, by means of the operation known as “pull” or “drag”, move the said assembled section to weld the same in its definitive position or simply to allow the addition of new pipes. The operation is carried out with the aid of traction provided by cables (normally wire ropes), coupled to a winch, dragging the section or moving the same over provisional rolls installed under the piping.
The main limitation of that method resides in the fact that the transported lengths must be relatively short, in order to keep the forces and mechanical demands generated by the traction within acceptable limits. Furthermore, the available lengths of the cables might impose limits on the distance to be traveled. For distances that are longer than the length of the cables, the traction device will have to be repositioned, which usually entails a procedure that is lengthy, expensive and not always feasible.
The classical methods of construction of duct line/pipelines still present other disadvantages when such lines are built in confined environments such as galleries where the height of these latter does not allow the access of the equipment required to handle mid-size to large-size piping, in addition to not constituting an adequate work environment for the professionals, who when working in such environments are frequently forced to adopt straining positions and are exposed to an absolutely unhealthy environment due to the gasses generated by the pipe welding operation itself.
One instance in which the system and method of the present invention find an immensely advantageous application consists in the construction of duct lines/pipelines over ships loading/unloading piers. In these cases, the pipelines run across distances over the water, on structures specifically built to support the same.
The assembly of duct lines/pipelines using known techniques is often carried out from barges wherefrom the pipes are laid, entailing significant logistical disadvantages, weather constraints and personal risks. If there is made an option to perform the assembly by pulling or dragging there must be made available winches, the traction stations must be repositioned, there must be run the risks inherent to the handling of wire rope and of damage to the piping. Furthermore, the welding of the spanning sections will have to be done over water, with all inconveniences entailed thereby.
By means of the system according to the present invention, the assembly of the piping becomes a remote operation and the installation thereof becomes sequential, using preassembled elements, thereby avoiding the above described hindrances.
One other example in which the system according to the present invention evidences an advantage is the assembly of a line inside a tunnel of circular cross section and low height, where the absence of proper work conditions and the confined environment render difficult the use of classical techniques.